High Wind Warning after thunderstorms

[Alex Lamers]

That was definately a wake low, probably similar to the one in Iowa Wednesday Afternoon too. High Wind Warnings issued up there. Wake lows can produce severe-criteria gusts. I have been through several already in the MCS-active Great Lakes zone. One produced some 60 mph gusts one morning which caused a lot of tree and powerline hits across the county.

They form behind decaying MCS's....when you see reflectivity and clouds start to wash out rapidly...that is an excellent sign.

Here is a good quote from a Memphis writeup...

Johnson and Hamilton (1988) proposed that wake lows were the result of subsidence warming which was maximized at the back edge of a trailing stratiform precipitation area where there was insufficient sublimation and evaporative cooling to offset adiabatic warming. Stumpf et. al. (1991) also concluded that the trailing stratiform precipitation region of mesoscale convective systems can be dynamically significant, by generating rapidly descending inflow jets at their back edges, producing pronounced lower-tropospheric warming, intense surface pressure gradients and strong low level winds. Similar conclusions were drawn by Zhang and Gao (1989) in a numerical modeling study. Recently, Gallus (1996) found, using a numerical modeling study, that when precipitation rates are prescribed to decrease with time, as might occur with collapsing precipitation areas, microphysical cooling may become sufficiently small as to induce strong subsidence and an intense wake low.

I don't like trying to explain them myself, I always trip all over my words. Bottom line, they occur behind decaying MCS's (although not all the time) and produce several hours of strong winds. I am not 100% sure, but I believe a heat burst and a wake low are different phenomina, which is why you probably didn't see a marked increase in temperatures.

...Alex Lamers...